Justin Bieber’s alleged assault of a Toronto limo driver on Dec.30 was reportedly triggered by the not-loud-enough volume of the vehicle’s radio, according to TMZ.

The American news outlet reports that Bieber’s people wanted the volume turned up higher as he cruised the Toronto entertainment district with an entourage.

The driver obliged, but just to a point.

When he wouldn’t turn it any louder, things got ugly, according to TMZ.

Meanwhile, in other Bieber news, a female Miami police officer finds herself under investigation after reportedly trying to take a photo of Bieber while he was under arrest in Florida last week for drag racing.

Making the drag racing incident more bizarre, there’s no evidence that he was actually racing, according to records TMZ claims to have obtained.

Miami police have already subpoenaed a video from TMZ which they suspect might show the former Stratford, Ont., resident racing.

The rented Lamborghini is capable of cheek-popping speeds, but it reached a maximum of only 71 km/h, according to the U.S. news outlet.

But Miami Police say he was clocked at speeds between 88-97 km/h.

He has pleaded not guilty to DUI, resisting arrest, and driving without a licence in relation to the incident.

If Bieber’s rattled, then he’s apparently cooling his nerves in the entertainment district of Toronto, as some media reports have him at Switch Nightclub, near King St. E. and Church St., until the wee hours of Friday.

Meanwhile, an American petition to have him deported continues to swell. It’s now at 138,000 signatures.

The White House must give a reply to any petition with more than 100,000 names.